The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
A typical modern multiple speed automatic transmission includes a plurality of planetary gear assemblies and selectively engaged friction clutches and brakes that achieve a plurality of forward speeds or gear ratios and reverse.
Increasingly demanding economic, performance and efficiency goals continue to encourage powertrain research and development. A result of this effort has been improvements relating to hybrid powertrains having automatic transmissions. The addition of electric motors to vehicle powertrains has multiplied engineering and design choices.
Whereas some electric motors are of relatively low power and function in supplemental or auxiliary and regenerative roles, others provide full operating power which may or may not be supplemented by another power source such as a small internal combustion engine.
In modern motor vehicle transmissions, the elements of a plurality of planetary gear assemblies are (1) connected by permanent coupling members, (2) selectively connected by friction clutches or (3) selectively grounded by friction brakes. Specific combinations of the clutches and brakes are engaged or activated in sequence to provide a predetermined sequence of numerically related gear ratios and thus output speeds and torques.
Due to the sophistication, performance and flexibility of such devices, they often become the basis of hybrid powertrains. The present invention relates to a four planetary gear assembly automatic transmission incorporating an electric motor.